// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/process/process_iterator.h"

#include <errno.h>
#include <stddef.h>
#include <sys/sysctl.h>
#include <sys/types.h>
#include <unistd.h>

#include "base/logging.h"
#include "base/macros.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"

namespace base {

ProcessIterator::ProcessIterator(const ProcessFilter* filter)
    : index_of_kinfo_proc_(0)
    , filter_(filter)
{
    // Get a snapshot of all of my processes (yes, as we loop it can go stale, but
    // but trying to find where we were in a constantly changing list is basically
    // impossible.

    int mib[] = { CTL_KERN, KERN_PROC, KERN_PROC_UID,
        static_cast<int>(geteuid()) };

    // Since more processes could start between when we get the size and when
    // we get the list, we do a loop to keep trying until we get it.
    bool done = false;
    int try_num = 1;
    const int max_tries = 10;
    do {
        // Get the size of the buffer
        size_t len = 0;
        if (sysctl(mib, arraysize(mib), NULL, &len, NULL, 0) < 0) {
            DLOG(ERROR) << "failed to get the size needed for the process list";
            kinfo_procs_.resize(0);
            done = true;
        } else {
            size_t num_of_kinfo_proc = len / sizeof(struct kinfo_proc);
            // Leave some spare room for process table growth (more could show up
            // between when we check and now)
            num_of_kinfo_proc += 16;
            kinfo_procs_.resize(num_of_kinfo_proc);
            len = num_of_kinfo_proc * sizeof(struct kinfo_proc);
            // Load the list of processes
            if (sysctl(mib, arraysize(mib), &kinfo_procs_[0], &len, NULL, 0) < 0) {
                // If we get a mem error, it just means we need a bigger buffer, so
                // loop around again.  Anything else is a real error and give up.
                if (errno != ENOMEM) {
                    DLOG(ERROR) << "failed to get the process list";
                    kinfo_procs_.resize(0);
                    done = true;
                }
            } else {
                // Got the list, just make sure we're sized exactly right
                size_t num_of_kinfo_proc = len / sizeof(struct kinfo_proc);
                kinfo_procs_.resize(num_of_kinfo_proc);
                done = true;
            }
        }
    } while (!done && (try_num++ < max_tries));

    if (!done) {
        DLOG(ERROR) << "failed to collect the process list in a few tries";
        kinfo_procs_.resize(0);
    }
}

ProcessIterator::~ProcessIterator()
{
}

bool ProcessIterator::CheckForNextProcess()
{
    std::string data;
    for (; index_of_kinfo_proc_ < kinfo_procs_.size(); ++index_of_kinfo_proc_) {
        kinfo_proc& kinfo = kinfo_procs_[index_of_kinfo_proc_];

        // Skip processes just awaiting collection
        if ((kinfo.kp_proc.p_pid > 0) && (kinfo.kp_proc.p_stat == SZOMB))
            continue;

        int mib[] = { CTL_KERN, KERN_PROCARGS, kinfo.kp_proc.p_pid };

        // Find out what size buffer we need.
        size_t data_len = 0;
        if (sysctl(mib, arraysize(mib), NULL, &data_len, NULL, 0) < 0) {
            DVPLOG(1) << "failed to figure out the buffer size for a commandline";
            continue;
        }

        data.resize(data_len);
        if (sysctl(mib, arraysize(mib), &data[0], &data_len, NULL, 0) < 0) {
            DVPLOG(1) << "failed to fetch a commandline";
            continue;
        }

        // |data| contains all the command line parameters of the process, separated
        // by blocks of one or more null characters. We tokenize |data| into a
        // vector of strings using '\0' as a delimiter and populate
        // |entry_.cmd_line_args_|.
        std::string delimiters;
        delimiters.push_back('\0');
        entry_.cmd_line_args_ = SplitString(data, delimiters,
            KEEP_WHITESPACE, SPLIT_WANT_NONEMPTY);

        // |data| starts with the full executable path followed by a null character.
        // We search for the first instance of '\0' and extract everything before it
        // to populate |entry_.exe_file_|.
        size_t exec_name_end = data.find('\0');
        if (exec_name_end == std::string::npos) {
            DLOG(ERROR) << "command line data didn't match expected format";
            continue;
        }

        entry_.pid_ = kinfo.kp_proc.p_pid;
        entry_.ppid_ = kinfo.kp_eproc.e_ppid;
        entry_.gid_ = kinfo.kp_eproc.e_pgid;
        size_t last_slash = data.rfind('/', exec_name_end);
        if (last_slash == std::string::npos)
            entry_.exe_file_.assign(data, 0, exec_name_end);
        else
            entry_.exe_file_.assign(data, last_slash + 1,
                exec_name_end - last_slash - 1);
        // Start w/ the next entry next time through
        ++index_of_kinfo_proc_;
        // Done
        return true;
    }
    return false;
}

bool NamedProcessIterator::IncludeEntry()
{
    return (executable_name_ == entry().exe_file() && ProcessIterator::IncludeEntry());
}

} // namespace base
